Interchange Improvements

1. Intersections at Interchanges

Table 5.6 shows the impact that potential intersection improvements identified in Chapter 4 would have on future PM peak-hour operating conditions at intersections located at or near Exits 182, 185, 186, and 187.

Table 5.6 Intersection LOS

Interchange Location and Intersection Level of Service Delay V/C Ratio No-Build Improved (sec/veh)

Exit 182 Outer Hammond and Odlin Rd E/D D 41.5 0.67 Exit 185 Falvey Street and Broadway

I-95 SB and Broadway I-95 NB and Broadway

A A 8.1 0.48

D C/D 34.2 0.81

C C 24.2 0.75

Exit 186 I-95 and Stillwater Ave

Bangor Mall and Stillwater Ave

C C 31.9 0.85

C C 23.8 0.73

Exit 187 Bangor Mall and Hogan Road I-95 SB and Hogan Road

The potential left-turn-lane improvements on eastbound and southbound approaches of the intersection of Odlin Road and Outer Hammond Street would reduce the delay and improve the level of service at that intersection from E/D (E, almost D) to LOS D.

Exit 185

The potential extension of the right-turn lane and redesignation of the left-turn lane on the intersection approach from the southbound off-ramp would reduce intersection delay and improve the level of service from D to C/D (C, almost D). Queues on the off-ramp approach would also be shortened. Other Broadway intersections at the Exit 185 interchange would maintain the same levels of service.

Exit 186

At the intersection of Stillwater Avenue and the Exit 186 ramps, the potential approach-lane modifications would provide a modest reduction in delay, but the level of service of the intersections would remain at C.

Exit 187

The potential action to increase right-turn capacity at the Hogan Road intersection with the southbound ramps would reduce delay and improve intersection level of service from

C to B. In addition, the action would reduce delay and improve the level of service from F to E at the intersection of Hogan Road and Bangor Mall Boulevard by improving the utilization of available lanes at that intersection.

2. Interchange Ramps

The impact of interchange ramp improvements was analyzed for Exits 182, 184, and 186, as well as a potential interchange north of Exit 187. Actions at Exit 182 and 184 are intended to improve the operation of those interchanges by relocating lanes at those locations. For the latter two locations, the main objective would be to relieve traffic congestion on Hogan Road, where Exit 187 provides access to Bangor Mall Boulevard and other commercial areas.

Exit 182

At Exit 182, two major options were identified to address safety and mobility issues: a median lanes option, which would shift through lanes toward the median to allow an additional auxiliary lane in each direction, and the flyover option, which would replace one of the cloverleaf loop ramps with a flyover ramp. Both would address one or more High Crash Locations and also provide mobility benefits for some of the interchange users.

Table 5.7 summarizes the overall impacts of the two options. The median lanes option would provide the larger amount of mobility benefit by reducing delays for I-95 traffic moving through the northbound and southbound weaving sections. These changes would address one high crash location. The flyover would address two high crash locations and provide mobility benefits for users of the flyover ramp.

Table 5.7 Exit 182 Interchange Options

Potential Action(s) Mobility Impact Safety Impact 2035 VHT Savings HCLs Addressed

Median Lanes 13644 1

Flyover 2685 2

Exit 184

At Exit 184, potential improvement actions could address three high crash locations: one on Union Street at the northbound ramps and two on I-95 at the northbound on-ramp.

Table 5.8 summarizes the safety impact of the improvement actions on the number of crashes at those locations. The closure of the Ohio Street cut-off ramp would reduce the number of crashes at the Union Street intersection, by eliminating a major pattern of crashes involving northbound off-ramp traffic attempting to cross Union Street. The shift in location of the northbound on-ramp would improve the safety of traffic merging into I-95 mainline traffic.

Table 5.8 Safety Impact of Exit 184 Improvement Actions

High Crash Location Number of Crashes Annual Change % Change

Union @ NB Ramps 9 -4 -44%

I-95 @ NB On-Ramp 12 -3 -25%

Combined 21 -7 -33%

Exits 186, 187, and Beyond

Improving traffic operations around the Exit 187 (Hogan Road) interchange is the main objective of potential major improvement actions at Exit 186 and north of Exit 187. Both the addition of a northbound on-ramp at Exit 186 and a new interchange at Mile 188 could provide some congestion relief to Hogan Road by diverting traffic that would otherwise be using Exit 187. Either action could be implemented along with the potential intersection improvements at Exit 187. Table 5.9 summarizes the 2035 traffic conditions at the Hogan Road intersections for the no-build condition, for the Hogan Road

intersection improvement actions, for the two major interchange actions, and for the combination of the intersection actions and each of the major interchange actions.

Table 5.9 Exit 187 Interchange Options

Potential Action(s) Exit 187 Intersection

Level of

Service Delay V/C Ratio (sec/veh)

No-Build Bangor Mall and Hogan Road

I-95 SB and Hogan Road I-95 NB and Hogan Road

F 101.5 0.86

C 22.1 0.78

C 28.7 0.88

Intersection Improvement Bangor Mall and Hogan Road I-95 SB and Hogan Road I-95 NB and Hogan Road

E 63.4 0.88

B 13.1 0.69

C 28.3 0.85

NB On-Ramp at Exit 186 Bangor Mall and Hogan Road I-95 SB and Hogan Road I-95 NB and Hogan Road

E 75.8 0.84

C 25.9 0.77

E/F 79.4 0.95

New Interchange (Exit 188) Bangor Mall and Hogan Road I-95 SB and Hogan Road with NB On-Ramp at Exit 186

Bangor Mall and Hogan Road I-95 SB and Hogan Road with New Interchange (Exit 188)

Bangor Mall and Hogan Road I-95 SB and Hogan Road I-95 NB and Hogan Road

D 53.9 0.88

B 13.7 0.92

C 31.6 0.86

As Table 5.9 shows, each of the individual actions would improve the LOS F at the intersection of Hogan Road and Bangor Mall Boulevard to LOS E. The intersection improvement action would also improve the LOS C at the southbound ramps intersection to LOS B. However, the additional Exit 186 ramp would likely reduce the LOS C at the Exit 187 northbound ramps intersection to LOS E because it would increase volumes between the interchanges for short-distance travel. Inclusion of the Hogan Road intersection improvement action would improve the effectiveness of either major interchange action, with a LOS D at the Bangor Mall Boulevard intersection. The combination of the intersection improvement action with a new interchange provided the best overall result, with all three of the Hogan Road intersections at LOS D or better.

E. Other

1. Signing

Although evaluating the potential impact of signing changes that would reduce conflict between I-95 through traffic and interchange traffic would be difficult, available traffic volume data shows that interchange traffic is a major component of the traffic stream.

Table 5.10 shows the amounts and percentages of traffic on mainline segments between interchanges that is composed of on-ramp traffic from the upstream interchange or off-ramp traffic to the downstream interchange.

Table 5.10 Ramp Traffic Between Interchanges

Direction Segment Mainline

AADT Northbound Exit 180 (Coldbrook) to Exit 182 (I-395)

Exit 182 (I-395) to Exit 183 (Hammond) Exit 183 (Hammond) to Exit 184 (Union) Exit 184 (Union) to Exit 185 (Broadway) Exit 185 (Broadway) to Exit 186 (Stillwater) Exit 186 (Stillwater) to Exit 187 (Hogan) Exit 187 (Hogan) to Exit 191 (Kelley)

13,130

Southbound Exit 191 (Kelley) to Exit 187 (Hogan) Exit 187 (Hogan) to Exit 186 (Stillwater) Exit 186 (Stillwater) to Exit 185 (Broadway) Exit 185 (Broadway) to Exit 184 (Union) Exit 184 (Union) to Exit 183 (Hammond) Exit 183 (Hammond) to Exit 182 (I-395) Exit 182 (I-395) to Exit 180 (Coldbrook)

15,600

On- and off-ramp traffic accounts for about 45 to 50% of the AADT on most mainline segments of I-95 through Bangor. The percentage is lower (around 30%) between Exits 183 and 184, but the percentage is higher (70 to 75%) between Exit 183 and Exit 180 (south of the Study Area). The volume of ramp traffic between Exits 183 and 182, at 15,200 northbound and 14,040 southbound, is also the highest in the Study Area. These volumes and percentages suggest that non-ramp traffic should be in the left lane,

especially in the Exit 182 area, to minimize conflicts between ramp traffic and through traffic.

The potential removal of “Keep Right Except to Pass” signs on the I-95 approaches to Bangor may help reduce the amount of through traffic using the right lane. If more action is needed to reduce the conflicts, overhead signing could be modified to encourage through traffic to use the left lane. This could be especially useful on the approaches to Exit 182 and could have an effect similar to the median lanes option by providing more separation between through traffic and ramp traffic at Exit 182.

2. Median Barrier

The potential action to install a concrete median barrier along the narrowest part of the I-95 median in Bangor would be intended to improve safety and reduce maintenance costs.

It would replace the guardrail and glare shields currently in use. Maintenance costs would be reduced by eliminating the need to repair guardrail and glare shields. Reduced need for repairs would improve the safety of highway maintenance workers and highway users by reducing the need to set up maintenance work zones on I-95. The concrete barrier would also reduce the likelihood of a vehicle straying across the median into the opposing flow of traffic.

However, a concrete barrier could have unintended consequences regarding crash safety.

Vehicles that leave the travel lanes and crash into a concrete barrier are more likely to rebound and reenter the travel lanes than vehicles that crash into a guardrail. A recent study of lane departure crashes on I-295 in Portland, Maine, showed that 57% of crashes into a concrete barrier rebounded into the travel lane while the percentage for crashes into guardrail was 26%. A full evaluation of the overall effectiveness of a median barrier would require a more detailed analysis beyond the scope of the Bangor I-95 Corridor Study.